Sustainable synthesis of branched-chain diesters

• Published in: Journal of biotechnology 2021-01, Vol.325, p.91-99
• Main Authors: Serrano-Arnaldos, Mar, Ortega-Requena, Salvadora, Sánchez, José Ángel, Hernández, Adrián, Montiel, María Claudia, Máximo, Fuensanta, Bastida, Josefa
• Format: Article
• Language: English
• Subjects: Biolubricants; Bis(2-ethylbutyl) adipate; Bis(2-ethylbutyl) sebacate; Lipase; Solvent-free
• ISSN: 0168-1656; 1873-4863
• DOI: 10.1016/j.jbiotec.2020.11.013

[Display omitted] •The environmentally-friendly biosynthesis of adipic and sebacic diesters is studied.•The evaporation of 2-ethyl-1-butanol is addressed by different reaction strategies.•The use of a fixed-bed reactor led to concentrations of 20–30 % (w/w) on diester.•Product concentrations of 75 % (w/w) were obtained by using a fed batch reactor.•High purity products were achieved with 2-ethyl-1-butanol excess in a batch reactor. Esters from branched alcohols and dicarboxylic linear acids are widely used as lube bases due to their good performance at low temperatures. This work proposes a new process to synthesize bis(2-ethylbutyl) adipate and bis(2-ethylbutyl) sebacate by using the lipase-based catalyst Novozym® 435 in a solvent-free system. Different reaction strategies have been tested in order to minimize 2-ethyl-1-butanol losses due to its evaporation and optimum operation conditions have been determined: 2.5 % of biocatalyst, 50 °C and a molar excess of alcohol of 15 % for the adipic diester and of 25 % for the sebacic one. It has also been proven that the immobilized enzyme can be reused in seven successive reaction cycles, achieving high yields without an appreciable reduction of activity. This biocatalytic pathway is a promising basis for the development of a more sustainable large scale process for obtaining biodegradable lubricants, as it is pointed out by productivity, economic and green metrics calculations.